Shore power - Page 4

Zephod_beeblebrox2 · 09-01-2015, 10:29 PM

Looking at my power usage
1040w microwave (10a)
Fridgfd (maybe 6a)
Kettle 10a
Slow cooker & steamer & coffee maker - unknown.
I'm highly unlikely to want to use more than 2 appliances simultaneously.

Redbear · 09-01-2015, 10:32 PM

Heating appliances and air conditioners are the heavy current draws.
Lights and entertainment devices not so much.

Since you are likely to want to have two cooking devices on at once, you may just want to set up a 30-amp shoreline and be done with it.

Zephod_beeblebrox2 · 09-01-2015, 10:47 PM

Quote:

Originally Posted by Redbear

Heating appliances and air conditioners are the heavy current draws.
Lights and entertainment devices not so much.

Since you are likely to want to have two cooking devices on at once, you may just want to set up a 30-amp shoreline and be done with it.

Yup. Wiring for 30+30, fusing for 15+15

Quote:

Originally Posted by Zephod_beeblebrox2

Looking at my power usage
1040w microwave (10a)
Fridgfd (maybe 6a)
Kettle 10a
Slow cooker & steamer & coffee maker - unknown.
I'm highly unlikely to want to use more than 2 appliances simultaneously.

bansil · 09-02-2015, 05:58 AM

thanks redbear for correction

Tango · 09-02-2015, 09:23 AM

One quick note when sizing your system...take the "start-up" amp draw into account for things like fridges & a/c's. They are typically several times what the running amps are. This true for both supply and wiring according to an electrician buddy.

Zephod_beeblebrox2 · 09-02-2015, 11:33 AM

The start up of my potential fridge is 5.6a, apparently. I think that is ridiculous. At 120v, that's 672W. That's one of those haier things. At that rate, I might be far better off with a Peltier cooler. Incidentally, if you use 13 Peltier elements, you can get -50 centigrade!

family wagon · 09-02-2015, 12:36 PM

Quote:

Originally Posted by Zephod_beeblebrox2

The start up of my potential fridge is 5.6a, apparently. I think that is ridiculous. At 120v, that's 672W. That's one of those haier things. At that rate, I might be far better off with a Peltier cooler. Incidentally, if you use 13 Peltier elements, you can get -50 centigrade!

High start-up current is common with motors. Some small refrigerators are work on a heat cycle instead; they're essentially an electric-only version of the RV propane fridge. Those wouldn't have high start-up current.

And yes, a stack of thermoelectric/peltier elements can get cold...... so long as you have a few kW available to power them, and don't need to chill anything more massive than a single raindrop or snowflake. For all the power they take in, they don't move very much power (heat) from the one side to the other.

bansil · 09-02-2015, 12:56 PM

maybe glue them all over the inside metal roof of the bus

roach711 · 09-02-2015, 01:33 PM

Quote:

Originally Posted by Zephod_beeblebrox2

One breaker feeds the left side of the sub panel. The other feeds the right side. The cable for each side is 30A.

Advantage... When I'm on a 30A circuit, both breakers in the mini box can be on. On a 15A circuit, I turn one off and just have two active sockets.

When you plug into 30 amp shore power your system up to the individual breakers will be protected by a 30 amp SP breaker as long as you use 10 gauge wire up to the box. When you plug into 15 amp SP you will be limited to 15 amps by the breaker at the SP panel. Thus, the weak spot in your system, your 15 amp rated extension cord, will be protected at the SP panel. No need for your second breaker box. Just be sure you run 10 gauge wire from the outside bus receptacle to the breaker box. As stated before, you don't need a main breaker in your bus breaker panel, just connect your incoming hot wire to one lug and jumper from it to the second.

Here's a 30A inlet receptacle similar to what you'll see on most newer RVs these days

30 Amp 125V Boat Power Inlet

Here's a good quality 30A power cord that will make a water tight seal to the Marinco receptacle

Marinco 30 Amp Shore Power Cordset

You can build your own cords but the price is almost what a manufactured cord will cost and you still have to find a good way to weather seal the connectors to the wire. These cords can be found used on eBay considerably cheaper than the new price.

Here's the correct way to wire 15A or 20A outlets

Wire An Outlet

Tango · 09-02-2015, 04:52 PM

Excellent info...thanks Roach!

Zephod_beeblebrox2 · 09-02-2015, 07:11 PM

Wow! I just looked for male wall socket s. Damn! A $6 piece if plastic and metal that's decidedly low tech going for $70. Can you say rip off?

I can see that my cables are most likely going to be inline sockets hidden behind an access panel. Just plug extension cables in!

family wagon · 09-02-2015, 07:52 PM

Yeah, the power inlet sockets are kind of outrageous. Especially the marine style. Here are a few that are more down-to-earth:
Reliance Controls PB31 for $49
Legrand L620 for $17, but it's just 20A and only 3-pole, so 120V with ground and neutral
Hubbell HBL2616 30A for $24 again 3-pole, 120 volt

but.. if the shore power cord has to be removable, there isn't anything wrong with having a short pigtail in the bus with a male cord end so that you can plug it to the female end of a shore power extension cable. With that, or with any of the other inlets as well, a proper transfer switch would be needed "some day" when an inverter finds its way into the bus to prevent the male terminals being energized when the inverter is turned on, or the inverter being turned on while the shore power is plugged in.

Zephod_beeblebrox2 · 09-02-2015, 07:54 PM

I was thinking that if I put some foirm of self contained power source, the pigtails coulkd becvome useful.

nat_ster · 09-02-2015, 11:43 PM

Home made cords just increase the risk of something being wired wrong by the individual that does not understand North American wiring standards.

Please for the sake of everyone, just buy the right stuff.

Nat

CaptainInsaneo · 09-03-2015, 02:45 AM

As someone who has halfassed a lot of things in life (including electric projects) I have come to learn a couple of things via first hand experience.

On a project the size of a bus buy the best things you can as you don't need much of it.

When it comes to electrical stuff oversize the wire and conduit sure it will cost more but make it so much easier to deal with later.

Try really really really hard not to have exposed live male adapters (more a problem in computers, thanks 3 pin fan connections).

Some times the exact thing you need is made, but only 10 other crazy people in the world buy one on any given day, therefore it is rare and rare things cost an absurd amount of money. Simply be happy you have a rare plug, it makes you special.

Other times the thing you need isn't made so you have to make it yourself. Don't cut corners when you do. It won't be easy, there is a reason they don't make what you are trying to make.

Also as long as you stick to one standard you will be just fine. If you use inches always use inches, if you always use centimeters... same goes for wiring if you use north american std then don't try to add other standards.

FOR THE LOVE OF GOD LABLE IN SHARPIE OR PAINT PEN!

mrblah · 09-03-2015, 06:59 AM

And when you label, label everything.

This means that the breaker gets a label of which items it protects frim surge and the item gets a label of which breaker its connected to.

If you have more than one panel, label the source and feed of the panels so in an emergency you know exactly which panel breaker to open.

That's what we do in many buildings we manage and it make everything easier...

Scooternj · 09-03-2015, 07:39 AM

Quote:

Originally Posted by CaptainInsaneo

FOR THE LOVE OF GOD LABLE IN SHARPIE OR PAINT PEN!

Or even better, get a P-touch style label maker.

jazty · 09-03-2015, 08:24 AM

Quote:

Originally Posted by Zephod_beeblebrox2

The start up of my potential fridge is 5.6a, apparently. I think that is ridiculous. At 120v, that's 672W. That's one of those haier things. At that rate, I might be far better off with a Peltier cooler. Incidentally, if you use 13 Peltier elements, you can get -50 centigrade!

If you piggyback 13 thermoelectric units (which would draw 65 amps @ 12v, or 780w) you could get -50c on the surface, but that wouldn't be enough to bring even a cooler down anywhere near that cold. Maybe 13 piggybacked units times 13 could bring a cooler close to that cold... And would draw 845 amps @12v (10000 watts) constantly!

A have a small compressor driven refrigerator that has a spike on startup, but levels out at around 5amps for its entire run and can bring the contents down to - 20c. I wouldn't even consider the thermoelectric units. They are Way too inefficient.

roach711 · 09-03-2015, 09:11 AM

Deleted message.

roach711 · 09-03-2015, 09:24 AM

Quote:

Originally Posted by Zephod_beeblebrox2

Wow! I just looked for male wall socket s. Damn! A $6 piece if plastic and metal that's decidedly low tech going for $70. Can you say rip off?

I can see that my cables are most likely going to be inline sockets hidden behind an access panel. Just plug extension cables in!

It appears that you're mounting all your outlets in one spot. If that's the case I can save you a lot of money. Just buy a 12 ga. 15A extension cord and a multi-outlet power strip like the ones people have under their desks at work. When you get to the campground, run the extension out the window and plug in your power strip. Walla! you have breaker protected, multi-outlet power at a fraction of the cost. Even better, you can move the power strip to the appliance instead of running those kludgy extension cords all over the place.

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